Characteristics of Perovskite Solar Cells under Low-Illuminance Conditions

Organic–inorganic perovskite solar cells have attracted much attention as high performance and low-cost photovoltaic devices. Because it consists of p-type hole transport layer, perovskite layer, and n-type electron transport layer similar to a p–i–n structure, it works effectively even under low-illuminance conditions, such as indoor lighting. In this work, we focused on the characteristics of perovskite solar cells under low-illuminance conditions, and a detailed investigation was carried out. The open-circuit voltage yielded at around 70% of AM1.5 at 0.1 mW/cm² illuminance, which is similar to that under indoor lighting. From impedance spectroscopy, it was suggested that the planar-type structure solar cell provided better resistance characteristics than that of the mesostructured cell for indoor applications. Comparing the characteristics of these types of solar cells, planar-type solar cells show higher voltage than mesostructured cells under low-illuminance conditions. These results have shown important implications for various applications of perovskite solar cells

Biotemplated Synthesis of TiO₂‑Coated Gold Nanowire for Perovskite Solar Cells

Fibrous nanomaterials have been widely employed toward the improvement of photovoltaic devices. Their light-trapping capabilities, owing to their unique structure, provide a direct pathway for carrier transport. This paper reports the improvement of perovskite solar cell (PSC) performance by a well-dispersed TiO₂-coated gold nanowire (GNW) in a TiO₂ cell layer. We used an artificially designed cage-shaped protein to synthesize a TiO₂-coated GNW in aqueous solution under atmospheric pressure. The artificially cage-shaped protein with gold-binding peptides and titanium-compound-biomineralizing peptides can bind GNWs and selectively deposit a thin TiO₂ layer on the gold surface. The TiO₂-coated GNW incorporated in the photoelectrodes of PSCs increased the external quantum efficiency within the range of 350–750 nm and decreased the internal resistance by 12%. The efficient collection of photogenerated electrons by the nanowires boosted the power conversion efficiency by 33% compared to a typical mesoporous-TiO₂-nanoparticle-only electrode